A mixture of MgH2 and Mg2FeH6 was synthesized by reactive ball milling of magnesium hydride and iron in hydrogen atmosphere. The material is highly nanocrystalline, with typical dimensions of the order of 10 nm; after hydrogen cycling at similar to 400 degrees C, well defined XRD peaks of Mg2FeH6 can be observed. Volumetric measurements of hydrogenation/dehydrogenation provide clear evidence of the presence of both hydrides even at lower temperatures. The relative content of magnesium-iron hydride increases on increasing H-2 cycling temperature, passing from similar to 44% at 335 degrees C to similar to 54% at 390 degrees C. Already at 250 degrees C the composite releases similar to 3wt% H-2 in similar to 1000 s, while above 340 degrees C, more than 4wt% H-2 can be discharged in less than 100s, following the Johnson-Mehl-Avrami-Kolmogorov equation, with an exponent n = 1, compatible with a reaction controlled transformation. Finally, also the electrochemical performances in a lithium cell have been investigated: the material is able to undergo a conversion reaction and gives on the first discharge more than 1400 mAhg(-1). The overpotentials decrease after materials activation by H-2 sorption treatments. Moreover, for the first time, the partial reversibility of the conversion reaction for materials containing magnesium iron hydride is here reported. (C) 2017 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.